//----------------------------------------------
//            NGUI: Next-Gen UI kit
// Copyright © 2011-2015 Tasharen Entertainment
//----------------------------------------------

using System.Collections.Generic;
using System.Diagnostics;
using System;

/// <summary>
/// This improved version of the System.Collections.Generic.List that doesn't release the buffer on Clear(),
/// resulting in better performance and less garbage collection.
/// PRO: BetterList performs faster than List when you Add and Remove items (although slower if you remove from the beginning).
/// CON: BetterList performs worse when sorting the list. If your operations involve sorting, use the standard List instead.
/// </summary>

public class BetterList<T>
{
    public BetterList()
    { }
    public BetterList(int cap)
    {
        buffer = new T[cap];
    }

    public T Pop(System.Type type)
    {
        if (buffer != null && size != 0)
        {
            for (int i = size - 1; i >= 0; --i)
            {
                if (buffer[i].GetType() == type)
                {
                    T v = buffer[i];
                    RemoveAt(i);
                    return v;
                }
            }
        }
        return default(T);
    }

    public T Pop(Func<T, bool> match)
    {
        if (buffer != null && size != 0)
        {
            for (int i = size - 1; i >= 0; --i)
            {
                T v = buffer[i];
                if (match(v))
                {
                    RemoveAt(i);
                    return v;
                }
            }
        }
        return default(T);
    }

#if UNITY_FLASH

	List<T> mList = new List<T>();
	
	/// <summary>
	/// Direct access to the buffer. Note that you should not use its 'Length' parameter, but instead use BetterList.size.
	/// </summary>
	
	public T this[int i]
	{
		get { return mList[i]; }
		set { mList[i] = value; }
	}
	
	/// <summary>
	/// Compatibility with the non-flash syntax.
	/// </summary>
	
	public List<T> buffer { get { return mList; } }

	/// <summary>
	/// Direct access to the buffer's size. Note that it's only public for speed and efficiency. You shouldn't modify it.
	/// </summary>

	public int size { get { return mList.Count; } }

	/// <summary>
	/// For 'foreach' functionality.
	/// </summary>

	public IEnumerator<T> GetEnumerator () { return mList.GetEnumerator(); }

	/// <summary>
	/// Clear the array by resetting its size to zero. Note that the memory is not actually released.
	/// </summary>

	public void Clear () { mList.Clear(); }

	/// <summary>
	/// Clear the array and release the used memory.
	/// </summary>

	public void Release () { mList.Clear(); }

	/// <summary>
	/// Add the specified item to the end of the list.
	/// </summary>

	public void Add (T item) { mList.Add(item); }

	/// <summary>
	/// Insert an item at the specified index, pushing the entries back.
	/// </summary>

	public void Insert (int index, T item)
	{
		if (index > -1 && index < mList.Count) mList.Insert(index, item);
		else mList.Add(item);
	}

	/// <summary>
	/// Returns 'true' if the specified item is within the list.
	/// </summary>

	public bool Contains (T item) { return mList.Contains(item); }

	/// <summary>
	/// Return the index of the specified item.
	/// </summary>

	public int IndexOf (T item) { return mList.IndexOf(item); }

	/// <summary>
	/// Remove the specified item from the list. Note that RemoveAt() is faster and is advisable if you already know the index.
	/// </summary>

	public bool Remove (T item) { return mList.Remove(item); }

	/// <summary>
	/// Remove an item at the specified index.
	/// </summary>

	public void RemoveAt (int index) { mList.RemoveAt(index); }

	/// <summary>
	/// Remove an item from the end.
	/// </summary>

	public T Pop ()
	{
		if (buffer != null && size != 0)
		{
			T val = buffer[mList.Count - 1];
			mList.RemoveAt(mList.Count - 1);
			return val;
		}
		return default(T);
	}

	/// <summary>
	/// Mimic List's ToArray() functionality, except that in this case the list is resized to match the current size.
	/// </summary>

	public T[] ToArray () { return mList.ToArray(); }

	/// <summary>
	/// List.Sort equivalent.
	/// </summary>

	public void Sort (System.Comparison<T> comparer) { mList.Sort(comparer); }

#else

    /// <summary>
    /// Direct access to the buffer. Note that you should not use its 'Length' parameter, but instead use BetterList.size.
    /// </summary>

    public T[] buffer;

    /// <summary>
    /// Direct access to the buffer's size. Note that it's only public for speed and efficiency. You shouldn't modify it.
    /// </summary>

    public int size = 0;

    public int Count
    {
        get { return size; }
    }

    public int Capacity
    {
        get { return buffer == null ? 0 : buffer.Length; }
    }

    /// <summary>
    /// For 'foreach' functionality.
    /// </summary>

    [DebuggerHidden]
    [DebuggerStepThrough]
    public IEnumerator<T> GetEnumerator()
    {
        if (buffer != null)
        {
            for (int i = 0; i < size; ++i)
            {
                yield return buffer[i];
            }
        }
    }

    /// <summary>
    /// Convenience function. I recommend using .buffer instead.
    /// </summary>

    [DebuggerHidden]
    public T this[int i]
    {
        get { return buffer[i]; }
        set { buffer[i] = value; }
    }

    /// <summary>
    /// Helper function that expands the size of the array, maintaining the content.
    /// </summary>

    protected virtual void AllocateMore()
    {
        T[] newList = (buffer != null) ? new T[Math.Max(buffer.Length << 1, 4)] : new T[4];
        if (buffer != null && size > 0) buffer.CopyTo(newList, 0);
        buffer = newList;
    }

    protected virtual void AllocateMore(int len)
    {
        T[] newList = new T[len];
        if (buffer != null && size > 0) buffer.CopyTo(newList, 0);
        buffer = newList;
    }

    public void EnsureSize(int size)
    {
        var capacity = this.Capacity;
        if (size > capacity)
        {
            int newBufferSize;
            if (capacity == 0)
            {
                newBufferSize = 4;
            }
            else
            {
                newBufferSize = capacity << 1;
            }
            if (size > newBufferSize)
            {
                do
                {
                    newBufferSize = newBufferSize << 1;
                }
                while (newBufferSize < size);
                AllocateMore(newBufferSize);
            }
            else
            {
                AllocateMore(newBufferSize);
            }
        }
        this.size = size;
    }

    /// <summary>
    /// Trim the unnecessary memory, resizing the buffer to be of 'Length' size.
    /// Call this function only if you are sure that the buffer won't need to resize anytime soon.
    /// </summary>

    void Trim()
    {
        if (size > 0)
        {
            if (size < buffer.Length)
            {
                T[] newList = new T[size];
                for (int i = 0; i < size; ++i) newList[i] = buffer[i];
                buffer = newList;
            }
        }
        else buffer = null;
    }



    /// <summary>
    /// Clear the array by resetting its size to zero. Note that the memory is not actually released.
    /// </summary>

    public void Clear() { size = 0; }

    /// <summary>
    /// Clear the array and release the used memory.
    /// </summary>

    public virtual void Release() { size = 0; buffer = null; }

    /// <summary>
    /// Add the specified item to the end of the list.
    /// </summary>

    public void Add(T item)
    {
        if (buffer == null || size == buffer.Length) AllocateMore();
        buffer[size++] = item;
    }

    public void AddRange(BetterList<T> temp)
    {
        if (temp.size == 0)
        {
            return;
        }
        var newSize = size + temp.size;

        if (buffer == null || newSize > buffer.Length)
        {
            //var newBufferSize = 4;
            //while (newBufferSize < newSize)
            //{
            //    newBufferSize = newBufferSize << 1;
            //}
            
            //System.Array.Resize(ref buffer, newBufferSize);

            EnsureSize(newSize);
        }
        System.Array.Copy(temp.buffer, 0, buffer, size, temp.size);
        size = newSize;
    }

    /// <summary>
    /// Insert an item at the specified index, pushing the entries back.
    /// </summary>

    public void Insert(int index, T item)
    {
        if (buffer == null || size == buffer.Length) AllocateMore();

        if (index > -1 && index < size)
        {
            for (int i = size; i > index; --i) buffer[i] = buffer[i - 1];
            buffer[index] = item;
            ++size;
        }
        else Add(item);
    }

    /// <summary>
    /// Returns 'true' if the specified item is within the list.
    /// </summary>

    public bool Contains(T item)
    {
        if (buffer == null) return false;
        for (int i = 0; i < size; ++i) if (buffer[i].Equals(item)) return true;
        return false;
    }

    /// <summary>
    /// Return the index of the specified item.
    /// </summary>

    public int IndexOf(T item)
    {
        if (buffer == null) return -1;
        for (int i = 0; i < size; ++i) if (buffer[i].Equals(item)) return i;
        return -1;
    }

    /// <summary>
    /// Remove the specified item from the list. Note that RemoveAt() is faster and is advisable if you already know the index.
    /// </summary>

    public bool Remove(T item)
    {
        if (buffer != null)
        {
            EqualityComparer<T> comp = EqualityComparer<T>.Default;

            for (int i = 0; i < size; ++i)
            {
                if (comp.Equals(buffer[i], item))
                {
                    --size;
                    buffer[i] = default(T);
                    for (int b = i; b < size; ++b) buffer[b] = buffer[b + 1];
                    buffer[size] = default(T);
                    return true;
                }
            }
        }
        return false;
    }

    /// <summary>
    /// Remove an item at the specified index.
    /// </summary>

    public void RemoveAt(int index)
    {
        if (buffer != null && index > -1 && index < size)
        {
            --size;
            buffer[index] = default(T);
            for (int b = index; b < size; ++b) buffer[b] = buffer[b + 1];
            buffer[size] = default(T);
        }
    }

    /// <summary>
    /// Remove an item from the end.
    /// </summary>

    public T Pop()
    {
        if (buffer != null && size != 0)
        {
            T val = buffer[--size];
            buffer[size] = default(T);
            return val;
        }
        return default(T);
    }

    /// <summary>
    /// Mimic List's ToArray() functionality, except that in this case the list is resized to match the current size.
    /// </summary>

    public virtual T[] ToArray() { Trim(); return buffer; }

    //class Comparer : System.Collections.IComparer
    //{
    //    public System.Comparison<T> func;
    //    public int Compare (object x, object y) { return func((T)x, (T)y); }
    //}

    //Comparer mComp = new Comparer();

    /// <summary>
    /// List.Sort equivalent. Doing Array.Sort causes GC allocations.
    /// </summary>

    //public void Sort (System.Comparison<T> comparer)
    //{
    //    if (size > 0)
    //    {
    //        mComp.func = comparer;
    //        System.Array.Sort(buffer, 0, size, mComp);
    //    }
    //}

    /// <summary>
    /// List.Sort equivalent. Manual sorting causes no GC allocations.
    /// </summary>

    [DebuggerHidden]
    [DebuggerStepThrough]
    public void Sort(CompareFunc comparer)
    {
        int start = 0;
        int max = size - 1;
        bool changed = true;

        while (changed)
        {
            changed = false;

            for (int i = start; i < max; ++i)
            {
                // Compare the two values
                if (comparer(buffer[i], buffer[i + 1]) > 0)
                {
                    // Swap the values
                    T temp = buffer[i];
                    buffer[i] = buffer[i + 1];
                    buffer[i + 1] = temp;
                    changed = true;
                }
                else if (!changed)
                {
                    // Nothing has changed -- we can start here next time
                    start = (i == 0) ? 0 : i - 1;
                }
            }
        }
    }

    /// <summary>
    /// Comparison function should return -1 if left is less than right, 1 if left is greater than right, and 0 if they match.
    /// </summary>

    public delegate int CompareFunc(T left, T right);
#endif
}
